JPH1080119A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a constitution capable of stabilizing the deflection of the axis of the rotary shaft, in a spindle motor of such type that the rotary shaft is supported by a sintered oil-retaining bearing. SOLUTION: In a spindle motor, the bearing material to support the rotary shaft 30 is a sintered oil-retaining bearing, so deflection occurs at the rotary shaft 30, being caused by clearance. Nevertheless, an eccentric hole 910 is made at the disc table 91 fixed to the rotary shaft 30, and the rotor is constituted positively so as to be of eccentric structure, so the rotary shaft 30 only causes periodic procession even if it deflects. If it is the deflection of drawing such a regular locus, the optical head can be made to follow the motion of a disc, so there is no hindrance in reproduction of information from the disc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor, and more particularly, to a structural technique for stabilizing the rotation of a rotating shaft.

[0002]

2. Description of the Related Art Among conventional spindle motors,
A spindle motor for driving a disk such as a CD-ROM includes a stator core having salient poles around which a core winding is wound, a driving magnet disposed to face the stator core, and a rotation that rotates integrally with the driving magnet. A rotor having a shaft and a ball bearing rotatably supporting the rotating shaft are configured. The rotor has a disk table fixed to a rotation shaft, and rotates the disk on the disk table. Here, a preload is applied to the ball bearing so that the rotating shaft does not swing, and the rotor including the disk table is configured such that the center of gravity is located on the axis of the rotating shaft so that the disk does not run out. Have been.

[0003] In the spindle motor configured as described above, the cost is being reduced by using a sintered oil-impregnated bearing instead of an expensive ball bearing.

[0004]

However, when a sintered oil-impregnated bearing is used in place of the ball bearing in the conventional motor structure, the rotation shaft cannot be used due to the clearance between the sintered oil-impregnated bearing and the rotation shaft. There is a problem that regular shake is likely to occur, and the optical head cannot follow the movement of the disk caused by such irregular shake, so that it is impossible to reproduce information from the disk. For example, when the axis direction of the rotating shaft is set to the Z direction among the X direction, the Y direction, and the Z direction which are orthogonal to each other, the runout of the rotating shaft when the sintered oil-impregnated bearing is used with the conventional motor structure is used. The state of the rotation shaft tip in the Y direction and the rotation shaft tip
Fig. 5 shows the displacement in the direction and the trajectory of the tip of the rotating shaft.
(A), (B), and (C) respectively show. As can be seen from these graphs, when the sintered oil-impregnated bearing is used with the conventional motor structure, the rotation of the rotating shaft is extremely irregular and the locus is not determined.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a spindle motor of a type in which a rotating shaft is supported by a sintered oil-impregnated bearing, capable of stabilizing the runout of the rotating shaft. To provide.

[0006]

In order to solve the above-mentioned problems, the present invention provides a stator core having salient poles wound with a core winding, a driving magnet opposed to the stator core, and an integral part of the driving magnet. In a spindle motor having a rotor having a rotating shaft that rotates, and a sintered oil-impregnated bearing that rotatably supports the rotating shaft, the rotor has a center of gravity of the rotor deviated from the axis of the rotating shaft. The eccentric part which defines the locus | trajectory when the said rotating shaft oscillates during rotation is characterized by the above-mentioned.

Various investigations have been made on the deflection of the rotating shaft in the spindle motor. When the center of gravity of the rotor is placed on the axis of the rotating shaft, if the rotating shaft starts to swing once, an irregular trajectory will be drawn. I found something.
On the other hand, when the center of gravity of the rotor is shifted from the axis of the rotating shaft as in the present invention, it has been found that although the rotating shaft oscillates, the rotating shaft causes a periodic sliding motion. In other words, if the rotor has an eccentric structure, it is possible to define the trajectory when the rotating shaft swings, and if the disk moves due to such regular swinging of the rotating shaft,
Since the optical head can follow, it is possible to reproduce information from the disk.

In the present invention, when the rotor has a disk table on which a disk is mounted, the eccentric portion may be formed on the disk table.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A spindle motor to which the present invention is applied will be described with reference to the drawings.

[First Embodiment] (Overall Structure) FIG. 1 is a longitudinal sectional view showing a right half of a spindle motor according to the present invention.

As shown in FIG. 1, in a spindle motor 1 to which the present invention is applied, a rotating shaft 30 is supported by a bearing member 20 with respect to a stator substrate 10, and the bearing member 20 is placed on the stator substrate 10. A flange portion 21 having a wide brim and a cylindrical portion 22 extending vertically from a central portion of the flange portion 21 are provided. Flange part 2
1 are provided on the stator substrate 10
And a core mounting surface 212 on which the stator core 60 is mounted. The cylindrical portion 22 of the bearing member 20 has a circular hole 220 into which the shaft 30 is inserted, and the flange portion 21 has a screwing groove 213 extending from the outer peripheral edge toward the center. Groove 213 for screwing
May be configured as a long hole or the like.

(Structure of Stator) The stator core 60
A plurality of core plates 61 each having a thickness of 0.5 mm are laminated, and each hole formed in the center of each core plate 61 forms a fixing hole 610. The bearing member 20 includes a flange 21
Are placed on the stator substrate 10, and the tubular portion 22 is fitted into the fixing hole 610 of the stator core 60. In this state, the stator core 60 is
1 and the stator fixing screw 7 penetrates through the stator core 60 and the screw groove 213 of the bearing member 20 from the upper surface of the stator core 60 from the upper surface of the stator core 60. Stopped at 10. Accordingly, the stator core 60 is fixed such that the flange portion 21 is sandwiched between the stator core 60 and the stator substrate 10, and the lower surface of the flange portion 21 (the contact surface 211 with the stator substrate 10) is in close contact with the stator substrate 10.

(Structure of rotor) The rotor 7 has a rotating shaft 3
0, a rotor case 50, a disk table 91 on which disks are installed, and the like, and can be integrally rotated. The rotating shaft 30 is inserted into the cylindrical portion 22 of the bearing member 20 and the thrust bearing 4 on the stator substrate 10.
Since it is supported by zero, it can rotate around the axis. A cup-shaped rotor case 50 is fixed to the rotating shaft 30, and the drive magnet 5 fixed to the inner peripheral surface thereof is fixed.
Reference numeral 1 faces the salient poles of the stator core 60 around which the core winding 62 is wound. The electronic components 11 mounted on the stator substrate 10 are chip components for constituting a motor drive circuit.

A disk-shaped disk table 91 for supporting a disk is fixed to the rotating shaft 30. The disk table 91 has a ring-shaped disk receiving rubber 92 stretched on an outer peripheral portion of an upper surface thereof. I have. Rotary axis 3
For 0, a centering 93, a center cap 94, and a chucking magnet 95 for holding the disc while centering it on the disc table 91 are also attached. A centering spring 96 is arranged between the centering 93 and the disk table 91.

(Structure of Bearing Member) In this embodiment, the bearing member 20 is a sintered oil-impregnated bearing obtained by impregnating a lubricating oil into a sintered part integrally including a flange portion 21 and the cylindrical portion 22. Inexpensive compared to ball bearings used in The bearing member 20 is provided on the inner peripheral surface of the cylindrical portion 22 at a position spaced apart in the axial direction of the rotating shaft 30.
Are provided with two sliding contact portions 221 and 222 for supporting. Therefore, of the inner peripheral surface of the cylindrical portion 22, the sliding contact portion 22
The region sandwiched between 1, 222 is a concave portion and is not in contact with the rotating shaft 30, and a slight gap 4 is formed between them. The sliding portions 221 and 222 are configured to be perpendicular to the contact surface 211 of the flange portion 21.

In the bearing member 20 formed of a sintered component, the sliding contact portions 221 and 222, the outer peripheral surface of the cylindrical portion 22, and the core mounting surface 212 of the flange portion 21 are all sizing-processed so that the pores are crushed. . For this reason, the lubricating oil impregnated in the bearing member 20 does not flow out unnecessarily. Further, the bearing member 20 has a sliding contact portion 221 on the inner peripheral surface of the cylindrical portion 22 itself,
Since the bearing 222 is formed, unlike the case where a bearing member is formed by assembling separate members, the number of parts and the number of assembling steps can be reduced. There is an advantage that a variation in the inner diameter of the portion 22) can be prevented. In addition, since the bearing member 20 is formed of an integrally sintered component, it is relatively easy to obtain the verticality of the sliding contact portions 221 and 222 with respect to the contact surface 211, and even this verticality is accurately performed. If it comes out, the sliding contact parts 221 and 22 to the stator substrate 10
A verticality of 2. Therefore, the verticality of the rotating shaft 30 can be accurately obtained. Further, unlike the configuration in which the bearing member 20 supports the rotating shaft 30 on the entire inner peripheral surface of the cylindrical portion 22, the two sliding contact portions 221 and 222 of the bearing member 20 support the rotating shaft 30 at positions separated from each other. Therefore, if even the sliding contact portions 221 and 222 are formed with high accuracy, the rotating rotary shaft 30 can be stably supported even if there are some irregularities in other portions. Further, the frictional resistance is small due to the small contact area. Moreover, an oil reservoir (gap 4) of the lubricating oil oozing out of the bearing member 20 is formed between the two sliding contact portions 221 and 222.

(Eccentric Structure of Rotor 7) Since a predetermined clearance is secured between the rotating shaft 30 and the bearing member 20 (sintered oil-impregnated bearing), the rotating shaft 30 swings during rotation. If the shake is irregular, the optical head cannot follow the movement of the disk, and information cannot be reproduced from the disk.

Therefore, in the present embodiment, as shown in FIG.
1, an eccentric hole 910 (eccentric portion) is formed at a position inside the disc receiving cover 92 so that the center of gravity of the rotor 7 deviates from the axis of the rotating shaft 30. Here, if the eccentric hole 910 is not formed, the disk table 91
Is located on the axis of the rotating shaft 30, so that the center of gravity of the disk table 91 is off the axis of the rotating shaft 30 in the direction indicated by the arrow A due to the formation of the eccentric hole 910. In addition, the rotor 7 as a whole also has a disk table 9.
If the eccentric hole 910 is not formed in 1, the center of gravity was on the axis of the rotating shaft 30. Therefore, the center of gravity of the rotor 7 was changed from the axis of the rotating shaft 30 to the direction indicated by the arrow A by forming the eccentric hole 910. It is out of position.

(Effect of this Embodiment) In the spindle motor 1 configured as described above, when the center of gravity of the rotor 7 is located on the axis of the rotating shaft 30, FIGS.
As described with reference to (C), when the rotating shaft 30 starts to swing once, an irregular trajectory is drawn.
If the center of gravity of the rotor 7 is deviated from the position of the axis of the rotating shaft 30 as in the present embodiment, even if the rotating shaft 30 oscillates, the sway is a periodic rubbing motion. For example, among the X direction, the Y direction, and the Z direction orthogonal to each other, when the axial direction of the rotating shaft 30 is the Z direction, a sintered oil-impregnated bearing is used as the bearing member 20 in the case of the motor structure according to the present embodiment. Even at this time, the state of the deflection of the rotating shaft 30 includes the displacement of the tip of the rotating shaft in the Y direction, the displacement of the tip of the rotating shaft in the X direction,
3 (A), (B), and FIG.
As shown in each of (C), the rotating shaft 30 only causes a periodic run-out. In other words, if the rotor 7 has an eccentric structure, the trajectory when the rotating shaft 30 swings can be defined. If the trajectory can be determined in this way, it becomes clear in which direction the rotating shaft 30 fluctuates. Therefore, the optical head can follow the movement of the disk caused by the deflection of the rotating shaft 30, so that information can be reproduced from the disk.

[Embodiment 2] In the above embodiment, the center of gravity of the rotor 7 is set at a position off the axis of the rotating shaft 30 by forming the eccentric hole 910 in the disk table 91 itself, as shown in FIG. As described above, the eccentric portion 9 is attached to the disc receiving rubber 92 stretched on the upper surface portion of the disc table 91.
20 may be provided. That is, in the present embodiment, the disk receiving rubber 92 is not completely ring-shaped, but is protruded inward to the extent that the disk table 9
An eccentric portion 920 is formed so that the center of gravity of one is shifted from the center in the direction of arrow B. Also in this case, the center of gravity of the disk table 91 and the rotor 7 was on the axis of the rotary shaft 30 unless the eccentric portion 920 was formed. At a position off the axis.

In the spindle motor 1 configured as described above, similarly to the first embodiment, the center of gravity of the rotor 7 is shifted from above the axis of the rotating shaft 30. Wake up. In other words, if the rotor 7 has an eccentric structure, the trajectory when the rotating shaft 30 swings can be defined. If the trajectory can be determined in this way, it becomes clear in which direction the rotating shaft 30 fluctuates. Therefore, the optical head can follow the movement of the disk caused by the deflection of the rotating shaft 30, so that information can be reproduced from the disk.

[Other Embodiments] When the center of gravity of the rotor 7 is shifted from the axis of the rotary shaft 30, the eccentric hole 910 or the eccentric hole is formed in the disk table 91 or the disk receiving rubber 92 stretched on the disk table 91. In addition to the method of forming the portion 920, for example, an eccentric hole may be formed in the rotor case 50 or the like.

[0023]

As described above, in the spindle motor according to the present invention, while using a sintered oil-impregnated bearing that is less expensive than a ball bearing to support the rotating shaft, the center of gravity of the rotor is adjusted to the axial center of the rotating shaft. Because it is located off the
Although the rotation axis has a run-out, the run-out is a periodic grinding motion. Therefore, according to the present invention, since the rotation axis only swings with a regular trajectory, the optical head can follow the movement of the disk. Therefore, there is no problem in reproducing information from the disc.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a right half of a spindle motor.

FIG. 2 is a plan view showing a structure of a disk table for making the rotor an eccentric structure in the spindle motor according to the first embodiment of the present invention.

FIGS. 3A, 3B, and 3C show, among X-direction, Y-direction, and Z-direction, which are orthogonal to each other, to show the state of rotation of a rotating shaft in a spindle motor to which the present invention is applied. When the axis direction of the rotating shaft is the Z direction, the displacement of the leading end of the rotating shaft in the Y direction, the displacement of the leading end of the rotating shaft in the X direction,
5 is a graph showing the trajectory of the rotating shaft and the tip of the rotating shaft.

FIG. 4 is a plan view showing a structure of a disk table (disk receiving rubber) for making the rotor an eccentric structure in the spindle motor according to the second embodiment of the present invention.

FIGS. 5A, 5B, and 5C are views of a rotation axis of a rotation axis of a conventional spindle motor, among X, Y, and Z directions orthogonal to each other; 9 is a graph showing the displacement of the tip of the rotating shaft in the Y direction, the displacement of the tip of the rotating shaft in the X direction, and the trajectory of the tip of the rotating shaft when the axial direction is the Z direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spindle motor 10 Stator board 20 Bearing member (sintered oil-impregnated bearing) 21 Flange part 22 Cylindrical part 30 Rotating shaft 60 Stator core 91 Disk table 92 Disk receiving rubber 910 Eccentric hole for making rotor eccentric structure 920 Eccentric structure of rotor Eccentric part for

Claims (2)

[Claims] 1. A stator having a salient pole wound with a core winding, a rotor having a driving magnet opposed to the stator core, and a rotating shaft rotating integrally with the driving magnet, and rotating the rotating shaft. A spindle motor having a sintered oil-impregnated bearing that freely supports the rotor, wherein the rotor has a center of gravity off the axis of the rotating shaft so that the locus of the rotating shaft swings during rotation. A spindle motor comprising an eccentric part for defining the following. 2. The spindle motor according to claim 1, wherein the rotor includes a disk table on which a disk is placed, and the eccentric portion is formed on the disk table.